The Universe, despite all the planets, stars, gas, dust, galaxies, and more we find within it, doesn't quite add up. On the largest cosmic scales, we find the same story everywhere we look: there isn't enough matter to account for the gravitational effects we observe. Matter clumps into a cosmic web; galaxy clusters grow to enormous sizes with fast-moving galaxies inside; individual galaxies rotate at large speeds that remain large all the way to their edges.
Without the presence of about five times as much matter as protons, neutrons, and electrons can account for, none of this would be possible. Our picture of the Universe requires dark matter for self-consistency. Yet, if dark matter is real, that means our Milky Way has a dark matter halo, too, and some of that matter passed through the Solar System, Earth, and even you. Here's how to know how much is inside you right now.
Might that explain why so many us get so dark sometimes? To read more, click here.